Dual chamber sealing element with hardening filler

ABSTRACT

A sealing element adapted to be disposed in a slitshaped, preferably annular gap, comprises an internal gas-filled cavity with an inlet in one end and an outlet in the other end for a hardening filling medium adapted to be introduced into the cavity under pressure so that the cavity is filled and the element is expanded so that the gap is sealed. The outlet (15) is connected to a closed chamber (14) adapted to receive the gas which is driven out of the cavity (2) in the flexible element when the cavity is filled with filling medium (16), so that the displaced gas can be compressed in the closed chamber (14&#39;) and exert a counter pressure on the filling medium (16&#39;) in the sealing element while the filling medium is hardening.

TECHNICAL FIELD

The invention relates to a sealing element comprising a flexible memberadapted to be disposed in a slit-shaped, preferably annular space. Morespecifically, the invention relates to a sealing element having aflexible member which comprises an internal air-filled cavity with ahardening filling medium intended to be introduced into said cavityunder pressure so that the cavity is filled and the member expands sothat the slit is sealed.

BACKGROUND ART

Expansible sealing elements are generally known and used to a wideextent for various purposes. It is also known to expand such sealingelements by means of a filling medium which is forced into a cavity inthe element after which the filling medium can harden so that theexpanded sealing shape of the sealing element is retained. Examples ofelements intended to be filled with a medium which, at least oninjection into the cavity, has the form of a liquid are disclosed interalia in FR Pat. No. 835 966, FR Pat. No. 1 375 644, DE Pat. No. 1 475890 and U.S. Pat. No. 2,760,791. In the U.S. Pat. No. 3,341,974 there isdisclosed a sealing element with an encircling cavity which expands fromone side of a partition round the sealing element to the opposite sideof the partition. Inlets and outlets for a liquid are disposed in bothend portions of the cavity, that is to say in the region adjacent to thetwo sides of the partition.

A limitation of the sealing elements of the general kind given above isthat, in the present stage of development, they are not particularlysuitable when the filling medium consists of a material with acomparatively long hardening time. This is actually a seriousdisadvantage because some of the filling media most suitable for otherreasons consist precisely of materials with comparatively long hardeningtimes. The reason why long hardening times constitute a problem is thatthe filling medium must retain excess pressure until the material hassolidified completely. With forms of embodiments of sealing elementshitherto known, therefore, the pressure source cannot be uncoupled untilthe material has solidified, which makes handling complicated and/orinvolves a low productivity expressed in number of sealing elementsfinished per unit of time. Against this background, rapid hardeningfilling media have hitherto mainly been used despite the fact that thesehave certain definite disadvantages, inter alia from the environmentpoint of view.

DISCLOSURE OF INVENTION

One object of the invention is to provide a sealing element which doesnot have the limitations indicated above. One object of the invention isthus to produce a sealing element of the kind indicated in the preamble,in which the filling medium may consist either of rapid hardening ofslow hardening material, the invention offering a specific advantageparticularly in the case of slow hardening material.

This and other objects and advantages can be achieved in that the cavityin the flexible member extends from the inlet such as to embrace thespace which shall be sealed and thereafter continues in a closed chamberadapted to be able to receive the air which is driven out of the liquidfilling medium when this is pressed into the cavity through the inlet,and preferably to be able to receive an excess quantity of fillingmedium so that the air in the closed chamber can be compressed and exerta counter pressure on the filling medium in the flexible member whilethe filling medium is solidifying. The air-filled cavity and the closedchamber may appropriately have the form of two chambers in one and thesame integrating body, the two chambers being in communication with oneanother through an outlet from the cavity which is to be filled with thefilling medium. According to a preferred form of embodiment, the chamberwhich consists of said closed chamber extends along at least a portionof the chamber which consists of the internal air-filled cavity which isto be filled with said filling medium. For example, the sealing elementhas the form of a sleeve with the two chambers arranged beside oneanother. According to a conceivable embodiment the two chambers may beintegrated without any marked connection therebetween, such that theflexible member basically consists of a preferably flat tube which hasan inlet in one end and is closed in the other end and having a lengthexceeding the circumferential length of the preferably annular spaceintended to be sealed. The closed end portion then will exceed beyondthe region of the inlet, said end portion being arranged in theslit-shaped space along at least a portion of the cavity intended to becompletely filled with a filling medium. According to one aspect of theinvention, the two chambers are further so dimensioned in relation toone another that the counter pressure which is produced in the closedchamber when the internal cavity is completely filled with a fillingmedium and excess of filling medium begins to flow into said closedchamber, preferably amounts to between 0.5 and 3 atm, preferably between1 and 2 atm.

Other aspects and advantages of the invention will be seen from thefollowing description of a preferred form of embodiment.

BRIEF DESCRIPTION OF DRAWINGS

In the following description of a preferred form of embodiment referenceis made to the accompanying figures of the drawings, of which:

FIG. 1 shows diagrammetically the sealing element according to thepreferred form of embodiment in the axial direction.

FIG. 2 is a section II--II on a larger scale.

FIG. 3 is a section III--III before a filling medium is injected.

FIG. 4 shows the same part of the sealing element as FIG. 3, after thefilling medium has been injected.

FIG. 5 illustrates how the sealing element can be used to seal a jointbetween outer pipes for insulating material for district heating pipes.

FIG. 6 illustrates how the sealing element according to the inventioncan be used to seal a pipe passage through a wall, and

FIG. 7 shows how the sealing element can seal the joint between two pipeends inserted one inside the other.

Only the details essential for an understanding of the invention areshown in the Figures, while other details are omitted so that theprinciples of the invention may be better brought out.

BEST MODE OF CARRYING OUT THE INVENTION

Referring first to FIGS. 1-3, a sealing element is generally designatedby 1. The sealing element 1 consists of a substantially flat tube orsleeve of natural rubber, synthetic rubber such as silicone rubber, orof mixtures of different qualities of rubber. Certain plastics materialsmay also be considered. The sealing element or sleeve 1, which,according to the form of embodiment, has the contour of a circular ring,comprises an internal cavity 2 with an oblique partition 3. Thepartition 3 extends between the two narrow side walls 4 and 5 of thesleeve 1. The two wider side walls of the sleeve 1 are designated 6 and7. The cavity 2 extends from one side 8 of the partition 3. In otherwords, the two sides 8 and 9 of the partition 3 constitute the two endsof the cavity 2 which extends through the whole sleeve. In the onenarrow side wall 4, an inlet 10 is formed near the side 8 of thepartition 3, the side 8 of the partition 3 forming a narrow angle to thenarrow side wall 4 of the cavity 2 in the region of the inlet 10. Theopposite side 9 of the partition 3 hence forms an oblique angle to theside wall 4. A nipple-shaped projection is designated 11, while aflexible tube for the supply of a filling medium, connected to thenipple 11 is designated 12.

At the side of the cavity 2 and separated from this by a longitudinalpartition 13, parallel with the narrow side walls 4 and 5, there isdisposed another cavity 14. As can be seen from FIGS. 2 and 3, the twochambers 2 and 14 are thus disposed beside one another, extendingparallel between the sides 8, 8' and 9 of the transverse partition 3.The cavity between the longitudinal partition 13 and the narrow outerwall 5 is also called "the closed chamber", because this chamber onlyhas an inlet 15 but no outlet. Thus the chambers 2 and 14 communicatewith one another through the passage 15 which at the same timeconstitutes an outlet for a filling medium from the internal cavity 2 tothe closed chamber 14. According to this form of embodiment, theinternal cavity 2 has a considerably larger volume than the closedchamber 14.

When the sealing element--the sleeve 1--is used, the sleeve is disposedin the gap which is to be sealed. After this, a hardening filling mediumis introduced through the flexible tube 12 into the internal cavity 2,in the part of said cavity which is bounded by the side 8 of thepartition 3. The filling medium, which is designated 16 in FIG. 4, ispressed round the whole sleeve into the internal cavity 2 until thefilling medium meets the opposite side 9 of the partition 3. After that,the internal cavity 2 is completely filled with filling medium 16 andthe wide walls 6 and 7 have moved away from one another throughexpansion of the internal cavity 2 as a result of the pressure which thefilling medium develops. When the internal cavity 2 is completely full,an excess quantity of filling medium is also forced into the closedchamber 14 through the passage 15 and is for this purpose guided towardsthe passage 15 by the sloping wall 9 of the partition 3 such that anygas-filled pocket will not remain in the cavity 2. The excess quantityof filling medium forced into chamber 14 is designated 17 in FIG. 4. Theconveying path of the filling medium is marked by arrows, FIG. 3.

The internal cavity 2 like the closed chamber 14 is at the start filledwith a gas, normally air. All this gas in the internal cavity 2 isforced into the closed chamber 14. More specifically, the gas is forcedinto that part 14' of the chamber 14 which is not filled with the excessquantity of filling medium 17. Thus an ever increasing gas pressuredevelops in the inner part 14' of the closed chamber 14. The injectionof the filling medium 16 may appropriately continue until the counterpressure in the inner part 14' of the closed chamber 14 substantiallycorresponds to the applied pressure in the supply tube 12. After this,the supply of further filling medium is broken off. The tube 12 isclosed by means of a clip 18 or the like, after which the tube 12 can becut off at the opposite side of the clip 18. A hardening epoxy oracrylic resin which develops heat during the solidification ispreferably used as a filling medium. This means that the pressure in thespace 14' further increases during the solidification process, so that aguarantee can be afforded for the fact that the expanding, sealing shapeof the sealing element 1 is retained during the whole of the hardeningphase, so that the sealing shape of the sleeve 1 becomes permanent.

FIG. 5 illustrates how a pair of sealing sleeves 1 according to theinvention is used to seal a joint between a pair of outer pipes 20a and20b for insulating material 21 for a district heating pipe 22. Theinsulating material 21 may consist, for example, of a cellular plasticsmaterial in the form of polyurethane foam. The district heating pipe 22consists of steel, while the outer pipes 20a and 20b consists ofpolyethylene of hard quality. A coupling sleeve 23 also consists ofpolyethylene. The sealing sleeves 1 are disposed in a gap 24 between thecoupling sleeve 23 and the pipes 20a and 20b. FIG. 5 illustrates thesituation when the sealing sleeves 1 have expanded so that the gap 24has been sealed at both sides of the joint 25 between the pipes 20a and20b. In this position, when the filling in the internal cavity 2 hashardened, the sealing sleeves constitute permanent seals of the gap 24at each side of the joint 25.

FIG. 6 illustrates in a corresponding manner how a sealing sleeve 1seals a passage 30 for a pipe 31 through a wall 32.

FIG. 7 illustrates a further example of an application. The Figure showsan axial section through a joint between two pipes 40 and 41 which areintroduced one inside the other. In this case, a sealing sleeve 1 sealsthe gap 42 between the two pipes 40 and 41.

I claim:
 1. A sealing element comprising a flexible member adapted to bedesposed in a slit-shaped, preferably annular space, which membercomprises an internal gas-filled cavity with an inlet on one end for ahardening filling medium intended to be introduced into said cavityunder pressure so that the cavity is filled and the member expands sothat the gap is sealed, characterized in that the cavity (2) in theflexible member extends from the inlet (10) such as to embrace the space(24, 30, 42) which shall be sealed and thereafter continues in a closedchamber (14) adapted to receive the gas which is driven out of saidcavity (2) in the flexible member when the cavity (2) is filled withfilling medium (16), so that the displaced gas can be compressed in theclosed chamber (14') and exert a counter pressure on the filling medium(16') in the flexible member while the filling medium is hardening.
 2. Asealing element as claimed in claim 1, characterized in that the closedchamber (14) extends along at least a portion of the internal gas-filledcavity (2) intended completely to be filled with a filling medium.
 3. Asealing element as claimed in one of the claims 1 and 2, characterizedin that the element 1 has the form of a sleeve with the two chambers (2,14) arranged beside one another.
 4. A sealing element as claimed in oneof the claims 1 or 2, characterized in that the two chambers are sodimensioned in relation to one another that the gas pressure which isdeveloped in the closed chamber when the filling medium begins topenetrate, is preferably between 0.5 and 3 atm, preferably between 1 and2 atm.
 5. A sealing element as claimed in one of the claims 1 or 2,characterized in that said internal gas-filled cavity (2) and saidclosed chamber (14) which is adapted to receive the displaced gas toprovide a counter pressure, constitute two chambers, communicating withone another through a passage (15), in one and the same integrated body.6. A sealing element as claimed in one of the claims 1 or 2,characterized by a partition (3) the two walls (8, 9) of whichconstitute the two end walls of said cavity (2), said inlet (10) beingprovided in a narrow side wall (4) of the cavity adjacent to saidpartition (3), the side wall (8) of the partition (3) forming a narrowangle to said narrow wall of said cavity (2) in the region of the inlet(10), and the opposite side wall (9) of the partition (3) forming anoblique angle to the same narrow side wall (4) of cavity (2).
 7. Asealing element as claimed in claim 6, characterized in that saidpassage (15) is provided adjacent to said opposite side wall (9) of thepartition (3) in the narrow angle between said side wall (9) and asecond narrow side wall (13) opposite to said first side wall (4).
 8. Asealing element as claimed in claim 7, characterized in that said secondnarrow side wall (13) is a partition between said cavity (2) and saidclosed chamber (14).